Re: [PATCH v6 06/40] arm64: mpam: Context switch the MPAM registers

[Ben Horgan]

Hi Jinjie,

On 05/11/2026 12:20, Jinjie Ruan wrote:
> 
> 
> 在 2026/3/13 22:45, Ben Horgan 写道:

> 
> Hi, everyone,
> 
> We found a problem as below:
> 
> In an offline/online co-located setup, MPAM gives the offline group a
> smaller MBW share, a softirq serving an online service runs with the
> PARTID of the throttled offline task it interrupted and is throttled
> with it -- a priority inversion.
> 
> Is this a known limitation?

Yes. The initial MPAM support was introduced with the userspace and kernel PARTID changing in
lockstep so that it matched the standard x86 setup. This left the way open for a generic resctrl way
to express that they may be different.

> 
> I see the following patchset uses a separate closid for kernel.
> 
> https://lore.kernel.org/all/cover.1790867441.git.babu.moger@xxxxxxx/
> 
MPAM should be able to work with that as outlined by Reinette [1].

[1] https://lore.kernel.org/lkml/2ab556af-095b-422b-9396-f845c6fd0342@xxxxxxxxx/

Thanks,

Ben